338 posts in this topic

aquatus1 7,057

It occurs to me that there needs to be a sort of neutral territory where people can talk about forces that affect our lives regardless of what sort of political intrigue presumably commands it from behind the curtains. Attempts to address things such as actual physics, chemistry, biology, or various other objective forces tend to be either ignored, dismissed, or most often, shouted down, rather than addressed.

At the same time, however, there is an acknowledgement that most of us simply aren't all that conversant with some of the sciences involved. Not a problem, as the sciences can be kept as simple as possible, while at the same time acknowledging that, in the real world, things are much more complex. Nor does it have to be strictly the empirical sciences either; probabilities, properly shown and supported, are welcome too.

I am proposing that, in this thread, we keep things to the pure science of a given situation. Never mind the secrets, or whodunnit, or plans for NWO, but just focus on the actual, academic, portion, of the many different conspiracies.

If nothing else, at least it will give people some way to rebut without relying on LOL!! as their main supporting argument.

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aquatus1 7,057

All right then, I thought a good example to start with is the collapse of the WTC floors. I've been seeing a claim that expresses incredulity at the claim that such a small portion of the tower could result in the total collapse of the floors underneath it unless there were explosives involved. This is usually backed up with videos of regular demolitions where the demolished building is cut more along the middle than the top (which, of course, begs the question as to how this wouldn't contradict the previous claim of explosives being placed at the top, but let's skip that for now).

Now, most people know the rejoinder to this is usually "Kinetic Energy!", but with little else to follow. While it is true that velocity adds energy to a moving object, few people really bother to take a good look at just how much energy we are talking about. Of course, in the real world there are many, many more variables involved, but for the purpose of answering the question of how just a few floors collapsing could result in a catastrophic failure of the entire tower, here is a very simplified version of how I understand it. I am by no means a master of physics, and mediocre at best on math, so feel free to correct me if you spot a mistake.

Let's start with our mental model of a tower: We have seven floors, each consisting of a slab of concrete, each with a mass of 200kg, which when converted to Newtons (a measure of force including the gravitational constant) results in 1960N. Magic support beams (no mass) hold the floors 3 meters from each other.

Now, between floors 5 and 6, a magic sword slices and vanishes the support beams. No longer supported, floors 6 and 7 succumb to the pull of gravity.

Floor 6 is 200kg of mass falling from a height of 3m at gravity constant (9.8m/s/s). Our formula for calculating kinetic energy (KE=1/2mv2) tells us that by the time floor 6 strikes floor 5, it will be moving at about 7.6m/s. That gives us our Velocity, but in order to calculate the force of the impact, we also need to know how much the floor continued to travel after striking. Let's be generous (to keep the math simple) and say that floor 6 "bounced" about .25m after hitting floor 5. Using our Force equation (Favgd=-1/2mv2), and plugging in the numbers (a 200kg floor falling 3m at a velocity of 7.6m/s with a stopping distance of .25m) and get an Impact Force of...23,104N.

Floor 5 was originally designed to hold the weight of 2 floors above it. Recall that each floor is 1960N, which means Floor 5 had to push up with at least 3960N to support both floors. Do the math and we get a downward force of 23,104N vs. an upward force of 3960N, which results in a downward force of 19,144N. Downward force wins. By more than x5.

But we are just getting started!

Edited May 28, 2013 by aquatus1

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RaptorBites 1,719

The problem I see with most truther observation of the towers is that each floor is built to withstand the entire building above it. Which is an absolute false assumption. Each floor is rated to withstand a static load, I believe 2-3 floors in total.

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psyche101 19,694

Now, most people know the rejoinder to this is usually "Kinetic Energy!", but with little else to follow.

I am guilty of this to be honest there seems little point in taking it further when this is simply brushed aside as a "disinformation tactic".

That being said, I applaud your effort and brilliant idea for a thread. Best to place science on the front foot to quell nonsense before it takes over the debate with personal opinion. Lovely job breaking down the kinetic energy argument into deliverable pieces.

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aquatus1 7,057

The problem I see with most truther observation of the towers is that each floor is built to withstand the entire building above it. Which is an absolute false assumption. Each floor is rated to withstand a static load, I believe 2-3 floors in total.

Yes and no, but you are right, from a construction engineer'spoint of view, that description is so simplistic as to be misleading. Similarly, I am afraid, I am about to throw out some numbers here that some of you will recognize as not actually being 100% correct in application towards engineering, but I am doing so just to try to explain an incredibly compex subject with the most basic formulas that people might recognize.

Sooo...that said:

In the real world, at this point in the collapse of the towers, the process is most accurately described as an avalanche, which cannot be calculated quite so simply as I am doing here. In an avalanche, there are forces working somewhat chaotically and infinitely randomly, to the point that we actually expect to see statistical improbabilities (including objects falling faster than freefall). Again, keeping this simple, just to give people an idea of the forces involved. We went from a slab with a mass of 200kg suddenly gaining the energy of a slab weighing over 23,000 kg just by falling 3m. Let's continue.

So, we have the results of ONE floor collapsing 3 meters. Gravity is by no means satisfied.

Now floors 5 and 6 are travelling downwards, but unlike before, they are not beginning from an At Rest position. Now the two floors have a mass of 400kg, and are moving downwards at a speed of 6.6m/s, slowed down a bit by the impact (hard to determine with collision equations, so I am assuming rather generously that the full avalanche was robbed of almost 90% of its strength in hitting floor 4, which is patently ridiculous). Since we have an Initial Velocity greater than zero, we use a different set of formulas (Motion Equations) to figure that if we have something moving at 6.6m/s and accelerating at 9.8 m/s/s for 3 m, we get a final velocity of 10.1m/s. Using our Impact formula like before, our two floors strike with a combined force of 81,608N.

Poor floor 4 was only ever meant to hold up 3 floors, with a combined total of 5880N. It gets utterly steamrolled by more than x13 that amount. Floor three gets hit .3 seconds later, math, math, math, impact velocity 36.4m/s, 1,589,952N. Floor 2, impact velocity 177m/s, 62,658,000N, Ground floor…yeah, not much left at this point.

As we can see, the amount of energy created by a collapsing floor is quite significant, and combined with the acceleration of gravity, rapidly reaches levels that humans simply cannot properly visualize?

Did anyone notice what I omitted from the above example, where 1 floor devastated the 5 floors below it?

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Little Fish 976

All right then, I thought a good example to start with is the collapse of the WTC floors. I've been seeing a claim that expresses incredulity at the claim that such a small portion of the tower could result in the total collapse of the floors underneath it unless there were explosives involved. This is usually backed up with videos of regular demolitions where the demolished building is cut more along the middle than the top (which, of course, begs the question as to how this wouldn't contradict the previous claim of explosives being placed at the top, but let's skip that for now).

Now, most people know the rejoinder to this is usually "Kinetic Energy!", but with little else to follow. While it is true that velocity adds energy to a moving object, few people really bother to take a good look at just how much energy we are talking about. Of course, in the real world there are many, many more variables involved, but for the purpose of answering the question of how just a few floors collapsing could result in a catastrophic failure of the entire tower, here is a very simplified version of how I understand it. I am by no means a master of physics, and mediocre at best on math, so feel free to correct me if you spot a mistake.

Let's start with our mental model of a tower: We have seven floors, each consisting of a slab of concrete, each with a mass of 200kg, which when converted to Newtons (a measure of force including the gravitational constant) results in 1960N. Magic support beams (no mass) hold the floors 3 meters from each other.

Now, between floors 5 and 6, a magic sword slices and vanishes the support beams. No longer supported, floors 6 and 7 succumb to the pull of gravity.

Floor 6 is 200kg of mass falling from a height of 3m at gravity constant (9.8m/s/s). Our formula for calculating kinetic energy (KE=1/2mv2) tells us that by the time floor 6 strikes floor 5, it will be moving at about 7.6m/s. That gives us our Velocity, but in order to calculate the force of the impact, we also need to know how much the floor continued to travel after striking. Let's be generous (to keep the math simple) and say that floor 6 "bounced" about .25m after hitting floor 5. Using our Force equation (Favgd=-1/2mv2), and plugging in the numbers (a 200kg floor falling 3m at a velocity of 7.6m/s with a stopping distance of .25m) and get an Impact Force of...23,104N.

Floor 5 was originally designed to hold the weight of 2 floors above it. Recall that each floor is 1960N, which means Floor 5 had to push up with at least 3960N to support both floors. Do the math and we get a downward force of 23,104N vs. an upward force of 3960N, which results in a downward force of 19,144N. Downward force wins. By more than x5.

But we are just getting started!

any structure that has "magic support beams" is going to collapse upwards towards the moon.

why don't you just do an experiment to demonstrate that 10 "floors" can destroy 100 "floors" all built structurally the same, also bear in mind that the "floor" does not hold up the building.

Or if you lack the imagination or resources, find the experiments on youtube that have already been done. you'll discover that any structure is incapable of destroying a larger object of the same structure in a collision.

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aquatus1 7,057

any structure that has "magic support beams" is going to collapse upwards towards the moon.

I thought it was pretty clear that the sole purpose of the support beams was to give us a picture in our heads, and had absolutely nothing to do with the numbers involved. I even said they had no mass. They are irrelevant.

why don't you just do an experiment to demonstrate that 10 "floors" can destroy 100 "floors" all built structurally the same, also bear in mind that the "floor" does not hold up the building.

If you like, we can use those numbers, but first I want to know if you understood the math as presented. If there is some part of it you did not understand, that needs to be addressed first, as using different numbers isn't going to make anything clearer.

find the experiments on youtube that have already been done. you'll discover that any structure is incapable of destroying a larger object of the same structure in a collision.

Of what possible interest would they be to me?

"the upper block of a falling structure will destroy itself well before it can possibly crush the entire larger lower structure"

Absolutely. Like I said, the collapse of the tower was more an avalanche than anything else.

this is incorrect.

Why are you applying the 3rd Law in a problem involving acceleration?

newton's third law !

"When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body."

Yes, that is indeed Newton's 3rd law. How are you applying it and why would it make the math incorrect?

Please explain why it is incorrect. As I stated in the OP, this thread is going to avoid the "single answer, no explanation" style of discussion. Newton's Laws of Motion are not holy words to be invoked as a self-evident answer to any question. It isn't enough to memorize the words. You actually have to understand it as well.

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Babe Ruth 4,839

In this hypothetical, or whatever it is properly called, is one allowed to examine the big picture? Is one allowed to examine the forensics involved with whatever the result of floor failure turns out to be?

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Little Fish 976

How does the state of the upper mass make any difference in its destructive force?

Regardless if it was "rigid" or in "little itty bitty pieces", the "entire mass" falling simultaneously within a fraction of a second still has enough weight to overload the floors below.

I suspect you are misspeaking using the term "weight", because if it "has enough weight to overload the floors below" then please explain how the building managed to stand for 30 years.

in any realistic destructive situation some mass will spill over the sides and through air spaces without collision, so there is going to be a difference when the top block is broken into pieces and those pieces strike/miss the solid bottom block. Those "itty bitty" forces only occur at the point of contact, a fraction of a second between those forces makes all the difference. throw some sand into the face a friend, then throw the equivalent weight in solid stone. which one cracks the head of your friend?

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Little Fish 976

Then I sympathize that you are unable to determine the difference between weight and mass.

weight is the force of gravity on a mass. in your example, the mass of the 50lb object is constant. gravity is also constant on this planet, so the weight of your 50lb mass is also constant on this planet.

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05854 16

It occurs to me that there needs to be a sort of neutral territory where people can talk about forces that affect our lives regardless of what sort of political intrigue presumably commands it from behind the curtains. Attempts to address things such as actual physics, chemistry, biology, or various other objective forces tend to be either ignored, dismissed, or most often, shouted down, rather than addressed.

At the same time, however, there is an acknowledgement that most of us simply aren't all that conversant with some of the sciences involved. Not a problem, as the sciences can be kept as simple as possible, while at the same time acknowledging that, in the real world, things are much more complex. Nor does it have to be strictly the empirical sciences either; probabilities, properly shown and supported, are welcome too.

I am proposing that, in this thread, we keep things to the pure science of a given situation. Never mind the secrets, or whodunnit, or plans for NWO, but just focus on the actual, academic, portion, of the many different conspiracies.

If nothing else, at least it will give people some way to rebut without relying on LOL!! as their main supporting argument.

Very interesting thread.

But where's the Conspiracy???

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Little Fish 976

my reading is that aquatus is trying to show that the wtc north tower could have collapsed without the aid of demolition devices. he has started with a model of floor slabs suspended in air like magic carpets. this alone invalidates any conclusion since it is the columns/walls that hold up a building. storey 1 needs to resist the weight of all storeys above it, but in aquatus model, storey one is only resisting the weight of 2 storeys. so the model fails there as well.
Edited May 28, 2013 by Little Fish

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shrooma 4,281

weight is the force of gravity on a mass. in your example, the mass of the 50lb object is constant. gravity is also constant on this planet, so the weight of your 50lb mass is also constant on this planet.

weight is the force of gravity on a mass. in your example, the mass of the 50lb object is constant. gravity is also constant on this planet, so the weight of your 50lb mass is also constant on this planet.

.

Force=Mass x Acceleration.

gravity & acceleration are both interchangeable and indestinguishable from each other.

a 50kg object at rest doesn't have the same mass characteristic as an accelerating 50kg object, which is why aquatos made the analogy of a weight at rest and an accelerating body. so your saying that gravity acting on mass as a constant is wrong. that's why you experience accelerative g-forces, not because you've suddenly become heavier, but because you've gained energy, E=Mc2 remember. the more energetic, the more mass, which is why only massless bodies can achieve light-speed, because the faster something is moving, the more massive it becomes.

you can't properly apply newton's third law to the problem of the collapsing floor due to momentum. the floor underneath the collapsing floor may respond with an equal force, but as the floor underneath's collapse point is well below the force being applied, there is no way for it to be sustained, so it WILL collapse.